Fabrication of bacterial cellulose with high efficient loading of Ag and TiO2 nanoparticles for removing organic dyes

As a new advanced oxidation technology, photocatalytic technology has broad application prospects in the field of wastewater treatment. However, in the actual use process, there will be difficulties in catalyst recovery and reuse. This article successfully prepared bacterial cellulose (BC) loaded silver and titanium dioxide nanoparticles (Ag-plated TiO₂/BC composite pellicle) by in situ embedding method. BC not only works as the carrier to load TiO₂ and Ag NPs but also adsorbs dyes to promote the reaction. As a reusable photocatalytic film, it is convenient to use and recycle in terms of testing and characterization compared with powders. The results show that Ag and TiO₂ nanoparticles were closely embedded in BC. We evaluated the photocatalytic degradation performance of the catalyst on methylene blue (MB), active red X-3B, and Rhodamine B. When the reaction time was 2 h, the dye removal rates were 71%, 68%, and 82.6%. At the same time, through the inhibition zone experiment, it was found that the material has a certain inhibitory effect on both Escherichia coli and Staphylococcus aureus. Therefore, the supported catalyst prepared by this method has the advantages of high catalytic activity, relatively stable property, easy recovery, and tailorability, making it potentially applicable in sewage post-treatment links.     

Coating the porous Al2O3 substrate with a natural mineral of Nontronite-15A for fabrication of hydrogen-permeable palladium membranes

Substrate surface modification is a key pretreatment during fabrication of composite palladium membranes for hydrogen purification in hydrogen energy applications. The suspension of a natural porous material, Nontronite-15A mineral, without any organic additives was employed in dip-coating of the porous Al₂O₃ substrate. The Nontronite-15A mineral was characterized by SEM, XRD, TG−DSC and granulometry analysis. The surface and cross-section of the coated porous Al₂O₃ tubes were observed by SEM, and their pore size distribution and nitrogen flux were also measured. Palladium membranes were fabricated over the coated Al₂O₃ tubes by a suction-assisted electroless plating. The optimal loading amount of the Nontronite-15A mineral is just to fill in and level up the surface cavities of the Al₂O₃ substrate rather than to form an extra continuous layer. A thin and selective palladium membrane was successfully obtained, and its permeation performances were tested. The kinetic analyses on the hydrogen flux indicate that the hydrogen permeation behavior exhibits typical characteristics for most of the palladium membranes. During the stability test at 450 °C for 192 h, no membrane damage was detected, and the hydrogen flux increased slightly.     

Nanoindentation and scratch behaviour of Ni–P electroless coatings

ABSTRACT

In the present paper, the mechanical properties and the scratch failure mechanisms of Ni–P electroless coatings are described. The material microstructure was studied in as-deposited and annealed conditions through SEM and EDS analyses. Nanoindentation measurements on the coatings showed a remarkable hardening due to the crystallization and precipitation behaviour produced by annealing. The scratch tests, conducted by increasing the load during scratch, revealed the coating failure mechanisms in a broad range of applied stresses up to delamination.     

Microstructure and properties of open-cell Ni–Sn–P alloy foams prepared by electroless plating

In this study, open-cell Ni–Sn–P alloy foams were prepared by electroless plating. The influence of tin content on the surface morphology and properties of Ni–Sn–P alloy foams were investigated. The surface structure of Ni–Sn–P alloy foams became more uniform and compact with the increase of Sn content. The X-ray diffraction result showed that Ni–Sn–P alloy foams gradually transformed from an amorphous structure into crystallization with the increase of heat-treatment temperature. The introduction of Sn significantly enhanced the corrosion resistance of Ni–P coatings in 3.5 wt% NaCl solution, the corrosion current density decreased from 5.022 to 0.805 μA/cm² and the corrosion potential shifted positively from −0.423 to −0.294 V after adding 5.96 wt% Sn to Ni–P coatings. However, the corrosion resistance of Ni–Sn–P foams was deteriorated after heat treatment. Adding Sn to the Ni–P system slightly weakened the compressive strength of Ni–P binary foams. Nevertheless, significant improvement in the antioxidant performance of Ni–Sn–P alloy foams was indicated by the reduction of the mass change rate in that the mass change rate of Ni–P foams obviously reduced from 5.15% to 0.25% after adding 5.96 wt% Sn.     

现代镀覆技术 第二部分──化学镀镍(续4)

给出了各种实用的化学镀镍配方及其工艺条件。     

硼氢化钠对滑轮用铸钢板化学镀Ni-B合金薄膜性能的影响

在滑轮用铸钢板上化学镀Ni-B合金薄膜,并研究了硼氢化钠的质量浓度对化学镀Ni-B合金薄膜性能的影响。结果表明:适当增加硼氢化钠的质量浓度,有利于增大化学镀Ni-B合金薄膜的厚度及硼的质量分数,从而提高化学镀Ni-B合金薄膜的硬度。当硼氢化钠的质量浓度大于1.2 g/L时,硼氢化钠的水解速率加快及剧烈的析氢反应,导致化学镀Ni-B合金薄膜的厚度及硬度有所降低。当硼氢化钠的质量浓度为1.2 g/L时,化学镀Ni-B合金薄膜表面"胞状"颗粒均匀、致密,摩擦因数和磨损率最低,具有最佳的耐磨性。     

Shear analysis of rice husk ash (RHA) reinforced tin-0.7-copper composite solders on electroless nickel/immersion silver (ENIAg) surfaces

In this study, the mechanical performance of the rice husk ash-reinforced tin-0.7 copper composite solder was investigated. 0.01 wt.%, 0.05 wt.% and 0.1 wt.% of rice husk ash (RHA) were added to the solder matrix to prepare the composite solders. In order, to replace the costly electroless nickel immersion gold surface finish on the copper substrate, the effect of electroless nickel immersion silver (ENIAg) as the surface finish was studied. The differential scanning calorimetry (DSC) analysis showed that the composite solder exhibited lower melting temperature relative to the plain solder owing to the inclusion of rice husk ash. Shear strength analysis was carried out to investigate the influence of rice husk ash and electroless nickel immersion silver surface finish on the shear strength of the developed composite solders. The results proved that the rice husk ash failed to enhance the shear strength of tin-0.7 copper lead-free solder with the plain solder exhibiting the highest shear strength.     

钕铁硼化学镀防护及在模拟海洋大气环境中的腐蚀行为

采用化学镀方法在钕铁硼表面分别制备Ni-P合金镀层、Ni-Mo-P合金镀层、Ni-P/PTFE复合镀层和Ni-Mo-P/PTFE复合镀层,并研究了不同化学镀层在模拟海洋大气环境中的腐蚀行为。结果表明:Ni-P合金镀层、Ni-Mo-P合金镀层、Ni-P/PTFE复合镀层和Ni-Mo-P/PTFE复合镀层都完整覆盖钕铁硼表面,它们的粗糙度差别不大,在模拟海洋大气环境中的腐蚀失重都低于钕铁硼的腐蚀失重,容抗弧半径增大且电荷转移电阻有不同程度的提高。与Ni-P合金镀层和Ni-Mo-P合金镀层相比,Ni-P/PTFE复合镀层和Ni-Mo-P/PTFE复合镀层具有优良的耐腐蚀性能,原因在于PTFE颗粒较均匀的沉积在镀层表面增加一道屏蔽层,也起到阻碍腐蚀介质渗透腐蚀的作用。尤其是Ni-Mo-P/PTFE复合镀层,其表面更致密,PTFE颗粒沉积更均匀,能更有效延缓腐蚀介质与钕铁硼接触,显著提高钕铁硼在模拟海洋大气环境中的耐腐蚀性能。     

稀土Ce对化学沉积Co-Fe-B合金涂层功能特性的影响

借助显微硬度计、磨损试验机和振动样品磁强计等分析稀土金属Ce对化学沉积Co Fe B合金涂层显微硬度、磨损体积、磁化强度、矫顽力和磁导率的影响。结果表明 ,稀土Ce明显地提高了涂层的显微硬度和耐磨性 ,随镀液中稀土Ce量增加 ,显微硬度和耐磨性先增后降 ,在 [Ce] =0 8g/L时达到最大值。稀土Ce还提高了涂层的饱和磁化强度和磁导率 ,降低了剩余磁化强度和矫顽力。     

Studies on copper coating on carbon fibers

1IntroductionMetal matrix composites reinforced by carbon fibers are promising composites for various applicationsdue to their high specific properties such as high specific strength and modulus ratio.However,applica-tions of such composites are li mited because of its interfacial problem:the lack of wetting of carbon fiberswith molten metals and a deterioration of the fiber properties during composite processing.To overcomethese problems,coatings can be deposited on fibers by various methods,…